piston question, flat or dish |
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piston question, flat or dish |
nycchef |
Jul 17 2008, 09:27 PM
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#1
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mechanical moron Group: Members Posts: 952 Joined: 28-November 05 From: new york city n.y. Member No.: 5,202 Region Association: None |
i have a set of mahle dish pistons from my 2.0. they seem perfect. i will be putting carbs and a web cam on it. what do i lose by staying with dish as opossed to flat. i'd like to save the $400. or so bucks.
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hydroliftin |
Jul 17 2008, 10:13 PM
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#2
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Member Group: Members Posts: 373 Joined: 8-November 06 From: Vallejo, CA Member No.: 7,180 Region Association: Northern California |
i have a set of mahle dish pistons from my 2.0. they seem perfect. i will be putting carbs and a web cam on it. what do i lose by staying with dish as opossed to flat. i'd like to save the $400. or so bucks. When I built my 2.0 the machinist cut the dished mahle pistons down on top to make them flat, then machined the bottom of the cylinders to raise the compression to 8.5 to 1. Works great. This was done by Jay of Jay's Machine Shop in Santa Clara, CA. He is an old school machinist and has worked his fair share of Porsche engines in his time. |
SGB |
Jul 17 2008, 11:06 PM
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#3
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just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
...machinist cut the dished mahle pistons down on top to make them flat, then machined the bottom of the cylinders to raise the compression to 8.5 to 1. Works great. I'm guessing he made the (shorter) pushrods for your hydroliftin cam? I don't guess it is enough to really see, is it? |
hydroliftin |
Jul 18 2008, 02:47 PM
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#4
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Member Group: Members Posts: 373 Joined: 8-November 06 From: Vallejo, CA Member No.: 7,180 Region Association: Northern California |
[/quote]
I'm guessing he made the (shorter) pushrods for your hydroliftin cam? I don't guess it is enough to really see, is it? [/quote] I bought the Isky "torquer" hydralic cam with matching lifters and push rods. As far as I know it did not require modifying the push rods, so the hydro lifters must be taking up the slack. In terms of compression ratio, the jugs were modified to sit deeper in the case, so compression ration was increased rather than decreased. Without modifying the cylinders, you are correct that a loss in compression ration would result. |
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